The Dutch integrated approach to monitor and calculate nitrogen deposition in Natura 2000 areas
The Netherlands have developed a tool to monitor the nitrogen deposition in Natura 2000 areas, called AERIUS. With the same tool, the impact of individual projects on the nitrogen deposition in Natura 2000 areas can be calculated. The tool accounts for both nitrogen oxides and ammonia. The unique combination of the monitoring function and the calculation function makes it possible to apply area-oriented approaches to reduce nitrogen deposition in Natura 2000 areas and to facilitate the spatial planning of economic activities.
The Netherlands have been very successful in reducing nitrogen deposition. The national average nitrogen deposition was between 2,500 and 3,000 mol nitrogen per hectare in the early-1990s. This has steadily declined to current levels of about 1,600 mol nitrogen per hectare. This is still too much for many sensitive ecosystems. The AERIUS tool was developed for determining the level of nitrogen deposition in Natura 2000 areas and the contribution of new projects and development plans (Heer et al., 2017). In this way, the system combines two important functions: monitoring the nitrogen deposition and calculating impacts of individual projects on Natura 2000 areas.